Mechanism for cranking automobiles and to prevent injury from back-firing of engines.



F. G.;PRESTON. MECHANISM FOR ORANKING AUTOMOBILES AND TO PREVENT INJURY PROM BACK FIRING 0P ENGINES.

APPLIOATIONIILED 1 mm, 1909.

95 3Z, Patented Mar. 7, 1911'.

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entree sra'r .FREDERIC G. PRESTON, OF MALDEN, MASSACHUSETTS.

MECHANISM FOR CRANKING AUTOMOBILES AND TO PREVENT INJURY FROM BACK- FIRING OF ENGINES.

Specification (if-Letters Patent.

' ?atented Mar. "7, 1911..

Application filed February 5, 1909. Serial No. 476,335.

To all whom it may concern:

Be it known that I, Fnnnnnro G. PRESTON,

allow it to turn forward, but will prevent it. from revolving backward, and having a suitable number of bevel teeth, of sufiicient pitch and depth to forcethe hand-crank or key away from its engagement with the shaft B, Fig. 1, which it engages in cranking or imparting the initial compression and motion to a gasolene engine; by the engagement of said crown-gear with a corresponding crowngear C having a corresponding number, pitch and depth of teeth attached to the hand-crank or key- I), substai'itially as shown in the accompanying drawings. The object of my said invention being to throw off or disengage the handcrank or key D from the shaft B or other direct or indirect connection with the crank shaft of the engine, in the process, or imparting the initial compression and motion to a gasolene engine in the event of back-firing or reversing of the engine, and preventing personal injury to the operator; it frequently happening that a gasolene engine particu larly on an automobile, will suddenly, without warning back-lire or start with a motion opposite to the motion intended and expected and thereby break the bone of the wrist of the operator and some times throw him with great force and cause him more serious injury.

The invention further consists in the construction and arrangement of parts as will be hereinafter described and particularly pointed out in the claim.

In the accompanying drawings, Fig. 1. is

a section of shaft hearing M, and the shaft.

B, with a section of the crown-gear or toothed-collar A upon 1t; held in place so as to prevent sliding longitudinally, by a pm P, which travels freely in an internal groove G cut in the bore of the crowngear A, and

allows the shaft to revolve within the crowngear A. On the reverse end of the crowng'ear A, are fine ratchet teeth 25 t engaged by a pawl S which prevents the crown-gear or toothed-collar A from revolving backward.

The shaft B see Fig. 1, is represented as usually made for application to automobiles with a crown-gear on its outer end to engage the hand-crank D when the-crankshaft of the engine is to he revolved by force of the hand-crank; the bevel teeth being intended to automatically disengage thehandcrank from the shaft, when the engine takes up the impulseand moves forward by its own force.

2 shows the hand-crank D with the shaft of the engine, forcing the pistons inand out, compressing the gas within the engine cylinder and carrying the engine to the sparking point where it should take up the motion by its own force, and by means of the bevel teeth on the'sliaft sliding away and riding up on the ends of the teeth of the hand-crank I), throw the handcrank out of engagement. With my invention applied, the same process is employed and in revolving the shaft by means of the handcrank D, the crown-gear C being attached by friction or otherwise to the hand-crank,

engages and revolves the loose crown-gear:

A upon the shaft B, but in the event of the engine back-firing or turning suddenly and unexpectedly backward the ratehetat the reverse end of A holds it from revolving backward and the crown-gear C slides backward and rides up over the ends of the bevel teeth and thereby forces the handcrank D off, or disengages it from the shaft 13, and thereby prevents personal injury to the operator.

The location of the pawl and ratchet upon the crown-gear A, is not material. It may be upon the peri hery of the gear if more convenient, or a riction gear ratchet or any substitute that allows the crown-gear A to tomatically any moving parts of machinery to'avoid loss or damage.

Claim. The combination with a shaft bearing having a toothed shaft mounted therein provided with teethon its outer end, a toothed collar mounted on said shaft provided with an internal groove therein and ratchet teeth on opposite ends thereof,-a pin on the shaft for engaging the groove and permitting rotation of'the shaft within the collar, ineans for engaging the teeth on one end of the collar to prevent backward rotation, a handcrank provided with teeth contacting with the teeth of the shaft, and a crown gear adapted to engage the teeth on the other end' 2 of said collar whereby the teeth of the handcrank are adapted to be automatically disengaged from the teeth of the shaft upon a backward motion of the shaft.

In testimony whereof I have affixed my 2 signature, in presence of two witnesses.

FEEDER-IO G. PRESTON. lVit-nesses:

JAMES F. PRESTON, THOMAS H. GRowELL.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D, C. 

